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Hydrochloric Acid Pickle Rubber Lining Tank Attack

I am graduate Material and Process Engineer with an Australian Ship Building Firm. I have recently been tasked with a problem in our Pipe Laundry. Our Hydrochloric Acid Pickle has developed a black film on the surface of the tank. The black film is easily removed by using chemical absorbent pads and will easily separate when transferred to a bulk container. Unfortunately the appearance of this black film has increased and has become an almost daily issue. We fear that the black rubber tank lining has failed after years of attack. Is our assumption correct and has anyone experienced similar problems dealing with Hydrochloric acid pickles?

Steve Manolitsas
- Melbourne, Victoria, Australia
2004

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2004

Unless your tank is very, very old it is not likely lined with rubber. The black lining which is almost universally used is PVC, commonly known by the trade name Koroseal. I have never seen a PVC liner degrade from exposure to HCl, but in the back of my mind I do seem to remember a rubber lined tank, of some antiquity, which did decompose.

Most likely your surface film is from oils on the parts you are pickling. Try skimming the surface and precleaning the parts before pickling.

Jeffrey Holmes, CEF
Spartanburg, South Carolina

Hi Steve,

Like many, MANY others, Steve, we don't get the full info, do we? What concentration of HCl? What temperature? What type of rubber was it? natural? Butyl, epdm, Hypalon?

Yes, carbon black can be added ... for rubbers, so a good source said, it increases the hardness to over 40 Shore A and contributes, like with ABS, in reducing UV attack.

My wild guess initially was that it was carbon black (5% to 6%) but Jeffrey Holmes had some good ideas. Give them a try.

Mind you, I'm plastics orientated ... and if you need something to last till the cows come home, then I'd have opted for ordinary gray PVC .... duly reinforced with FRP, the dual laminate approach.

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).
2004